1. Technical Field
The invention relates to a joining material for an electronic component, such as capacitors, inductors, resistors, stacked type and coaxial type dielectric filters, stacked type LC filters, composite LC components and composite LCR modules, an electronic component and a method for manufacturing same.
2. Related Arts
When manufacturing a stacked type dielectric filter, a paste for an internal layer electrode is printed on each of a predetermined number of greensheets, which are then laminated to produce laminated greensheets. These laminated greensheets are then sintered at a temperature of 700xc2x0 C. to 1100xc2x0 C. to produce a base body with the internal layer electrodes. After the base body is polished, a metal paste for an outer electrode is printed on predetermined regions on the surface of the body and fired to form the outer electrodes. A composite LC filter with an inductor and capacitor is also known.
When producing such composite electronic components, a predetermined number of greensheets for, for example, a dielectric layer and magnetic layer are laminated to provide laminated greensheets, which are then co-fired to join the magnetic and dielectric layers. It is also known to provide a greensheet of a joining layer between the greensheets of the magnetic and dielectric layers to provide laminated greensheets which are then co-fired. In Japanese publication Tokkohei 120605/1995, a ceramic material, obtained by firing a mixture of ZnO, TiO2, an CuO, is used for the joining layer for preventing peeling between the dielectric layers and magnetic layers and diffusion of the ingredients of both layers with each other. In Japanese patent application publication Tokkaihei 36913/1997, a ceramic material is provided between the dielectric and magnetic layers for improving the adhesive strength of the layers and for preventing diffusion of the ingredients of both layers with each other, the ceramic material being obtained by mixing a glass contained in the dielectric layer with a ceramic of 15 to 40 mol % of BaO and 60 to 85 mol % of TiO2 and firing.
However, according to the inventor""s research, warp may occur in the magnetic or dielectric layer depending on the compositions of both layers and their firing schedule. When the amount of warp is out of the specification for manufacturing a filter, such filter with impermissible warp is discarded as being defective, thus decreasing its manufacturing yield. The inventors further found that warp was also induced in the layers during the sintering process.
The object of the invention is, in an electronic component having a plurality of functional layers each selected from a magnetic layer and dielectric layer and joined with each other, to prevent warp in the magnetic layers or the dielectric layer.
The invention provides a joining material for an electronic component having a plurality of functional layers each selected from a magnetic layer and dielectric layer, the functional layers being joined with the joining material to each other, the joining material comprising a glass and a composition of a mol % of ZnO, b mol % of BaO and c mol % of TiO2 (a=12-45, b=4-45, c=18-81, a+b+c=100), wherein 0.1 to 10 weight parts of the glass is added to 100 weight parts of the composition.
The invention also provides a joining material for the electric component, the joining material comprising a glass and a composition of a mol % of ZnO, b mol % of BaO, c mol % of TiO2 and d mol % of MnO (a=12-45, b=4-45, c=18-81, dxe2x89xa610, a+b+c+d=100), wherein 0.1 to 10 weight parts of the glass is added to 100 weight parts of the composition.
The invention also provides a joining material for the electric component, the joining material comprising a glass and a composition of a mol % of ZnO, b mol % of BaO, c mol % of TiO2 and e mol % of Al2O3 (a=12-45, b=4-45, c=18-81, exe2x89xa610, a+b+c+e=100), wherein 0.1 to 10 weight parts of the glass is added to 100 weight parts of the composition.
The invention also provides a joining material for the electric component, the joining material comprising a glass and a composition of a mol % of ZnO, b mol % of BaO, c mol % of TiO2, d mol % of MnO and e mol % of Al2O3 (a=12-45, b=4-45, c=18-81, dxe2x89xa610, exe2x89xa610, a+b+c+d+e=100), wherein 0.1 to 10 weight parts of the glass is added to 100 weight parts of the composition.
The invention also provides an electronic component having the functional layers and a joining layer for joining the adjacent functional layers, wherein the joining layer is composed of a sintered product of each of the joining materials. That is, a layer composed of each of the joining materials is fired to form the joining layer. The joining layer is made of the sintered product obtained by firing the joining material.
The invention also provides an electronic component having the functional layers and a joining layer, wherein the joining layer is composed of sintered product showing at least one of a peak corresponding to BaNd2Ti5O14 and a peak corresponding to BaNd2Ti4O12 when measured by means of powdery X-ray diffraction method.
The invention also provides a method for manufacturing an electronic component having the functional layers and a joining layer, the method comprising the steps of:
laminating the functional layers already sintered to provide a laminated body, wherein a layer made of each of the joining materials is provided, and
firing the joining material to form the joining layer.
The invention also provides a method for manufacturing an electronic component having the functional layers and a joining layer, the method comprising the steps of:
laminating greensheets, for the functional layers, to provide laminated greensheets, wherein a layer made of each of the joining materials is provided, and
firing the laminated greensheets with the layer made of the joining material to form the functional layers and the joining layer.
The inventors researched the above described warp of a dielectric layer or magnetic layer and finally made the following discovery. According to state-of-the-art knowledge, it is possible to improve the adhesive strength and therefore to prevent the peeling of the magnetic and dielectric layers, by adjusting the thermal expansion coefficient of joining ceramics between the magnetic and dielectric layers to those of both layers.
However, in actual manufacturing, depending on the selection of materials for the magnetic and dielectric layers and sintering schedule, even when the thermal coefficient of the joining ceramics is adjusted to those of the magnetic and dielectric layers, warp may be observed during the sintering process. This phenomenon probably means that the magnetic, dielectric and joining layers shrink at different firing shrinkage rates at certain or even almost any time point during the sintering.
The inventors, based on the above discovery, successfully provide a solution. That is, the above warp may be considerably decreased or even prevented, on a wide variety of materials for magnetic and dielectric layers, by providing a joining material according to the above specific compositions.
In the above compositions, for further reducing the warp of the magnetic or dielectric layer, a content of ZnO (a mol %) may preferably be 25 to 40 mol %, a content of BaO (b mol %) may preferably be 5 to 15 mol %, and a content of TiO2 (c mol %) may preferably be 45 to 65 mol %.
A glass contained in the inventive joining material may preferably be selected from a group consisting of ZnOxe2x80x94SiO2xe2x80x94B2O3 glass, PbOxe2x80x94B2O3xe2x80x94SiO2 glass, Al2O3xe2x80x94CaOxe2x80x94B2O3xe2x80x94SiO2 glass, B2O3xe2x80x94SiO2 glass, MgOxe2x80x94Al2O3xe2x80x94SiO2 cordierite glass, and ZnOxe2x80x94MgOxe2x80x94Al2O3xe2x80x94SiO2 cordierite glass, and most preferably be ZnOxe2x80x94SiO2xe2x80x94B2O3 glass. These glasses may further contain TiO2, ZrO2 or Y2O3.
The greensheets for the inventive joining layer may be made brown, by adding not more than 10 mol % of MnO to the inventive joining material, to distinguish the brown-colored greensheet from greensheets for magnetic and dielectric layers. The joining layer may also be colored by adding at least one metal oxide selected from a group consisting of Cr2O3, Fe2O3 and NiO.
Not more than 10 mol % of Al2O3 may be added to the inventive joining material to further improve the adhesive strength of functional layers. Not more than 10 mol % of at least one metal oxide selected form a group consisting of Y2O3 and ZrO2 may be also added to the inventive joining material to further improve the adhesive strength of adjacent functional layers.
More than 10 mol % of MnO added to the joining material might reduce the adhesive strength between the functional layers. More than 10 mol % of Al2O3 added to the joining material might increase the warp of functional layers.
In the invention, at least one of the functional layers functions as an element in an equivalent circuit, and therefore functions as an electronic device layer. Such electronic device layer includes inductor, capacitor and resistor layers. The inductor layer may preferably comprise a magnetic layer and an inductor, such as a coil, as a conductor embedded within the magnetic layer. The capacitor layer may preferably comprise a dielectric layer and a capacitor as a conductor embedded within the dielectric layer. The magnetic layer means a layer made of a magnetic material, in the invention.
The invention is particularly suitable for a composite electronic component, preferably being an LC filter, stacked type dielectric filter or an LCR integrated substrate.
The dielectric layer may be preferably made of a TiO2, TiO2 CaO, BaOxe2x80x94TiO2, BaOxe2x80x94TiO2xe2x80x94Nd2O3, BaOxe2x80x94TiO2xe2x80x94Nd2O3xe2x80x94Bi2O3, BaO TiO2xe2x80x94ZnO, BaOxe2x80x94Al2O3xe2x80x94SiO2, MgOxe2x80x94CaOxe2x80x94TiO2, BaOxe2x80x94MgOxe2x80x94Ta2O5 or Al2O3 series oxide. Such oxide may include a glass, which is preferably selected from B2O3xe2x80x94SiO2, CaOxe2x80x94B2O3xe2x80x94SiO2, CaOxe2x80x94Al2O3xe2x80x94B2O3xe2x80x94SiO2 and CaOxe2x80x94Al2O3xe2x80x94TiO2xe2x80x94SiO2 series glasses.
The magnetic layer may preferably be made of a Fe2O3xe2x80x94NiOxe2x80x94CuOxe2x80x94ZnO, Fe2O3xe2x80x94NiOxe2x80x94CuOxe2x80x94ZnOxe2x80x94SiO2, NiOxe2x80x94ZnO, or CuOxe2x80x94ZnO or feroux planar series oxide. These magnetic material may contain not more than 5 weight percent of CoO or MnO, and about 1 weight percent of SiO, CaO, PbO, or Bi2O3 constituting a glass. When applying these materials, warp may be induced more often, thus increasing the need for the invention.
When the joining layer has a thickness of not smaller than 10 xcexcm, an amount of warp may be considerably reduced and the tensile strength thereof may be improved. The upper amount of the thickness is not particularly limited, however, the layer with a thickness of not larger than 500 xcexcm is practical.